linux-kernel - Re: [PATCH] PM / sleep: Mechanism to find source aborting kernel suspend transition

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Date:   Sat, 9 Dec 2023 16:26:54 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Vimal Kumar <vimal.kumar32@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PM / sleep: Mechanism to find source aborting kernel
 suspend transition

Le 09/12/2023 à 09:10, Vimal Kumar a écrit :
> Sometimes kernel suspend transitions can be aborted unconditionally by
> manipulating pm_abort_suspend value using "hard" wakeup triggers or
> through "pm_system_wakeup()".
> 
> There is no way to trace the source path of module or subsystem which
> aborted the suspend transitions. This change will create a list of
> wakeup sources aborting suspend in progress through "hard" events as
> well as subsytems aborting suspend using "pm_system_wakeup()".
> 
> Example: Existing suspend failure logs:
> [  349.708359] PM: Some devices failed to suspend, or early wake event detected
> [  350.327842] PM: suspend exit
> 
> Suspend failure logs with this change:
> [  518.761835] PM: Some devices failed to suspend, or early wake event detected
> [  519.486939] Abort: ws or subsystem uart_suspend_port aborted suspend
> [  519.500594] PM: suspend exit
> 
> Here we can clearly identify the module triggerring abort suspend.
> 
> Co-developed-by: Chinmoy Ghosh <chinmoyghosh2001@...il.com>
> Signed-off-by: Chinmoy Ghosh <chinmoyghosh2001@...il.com>
> Co-developed-by: Mintu Patel <mintupatel89@...il.com>
> Signed-off-by: Mintu Patel <mintupatel89@...il.com>
> Co-developed-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vimal Kumar <vimal.kumar32@...il.com>
> ---

...

> +void pm_add_abort_suspend_source(const char *source_name)
> +{
> +	struct pm_abort_suspend_source *info = NULL;

No need to init.

> +
> +	info = kmalloc(sizeof(struct pm_abort_suspend_source), GFP_KERNEL);

Could be sizeof(*info).

> +	if (unlikely(!info)) {
> +		pr_err("Failed to alloc memory for pm_abort_suspend_source info\n");

No need to log a message if kmalloc() fails, a trace is already logged.

> +		return;
> +	}
> +
> +	/* Initialize the list within the struct if it's not already initialized */
> +	if (list_empty(&info->list))
> +		INIT_LIST_HEAD(&info->list);
> +
> +	info->source_triggering_abort_suspend = kstrdup(source_name, GFP_KERNEL);
> +	if (unlikely(!info->source_triggering_abort_suspend)) {
> +		pr_err("Failed to get abort_suspend source_name\n");

Same here.

> +		kfree(info);
> +		return;
> +	}
> +
> +	list_add_tail(&info->list, &pm_abort_suspend_list);

...

CJ